technical note - tn 004: 2015 - transport for nsw · • all underboring, excavation, piling, or...

Technical Note - TN 004: 2015

© State of NSW through Transport for NSW of 2

Technical Note - TN 004: 2015 Issued date: 03 September 2015

Effective date: 03 September 2015

Subject: Buried services at turnouts and special trackwork

This technical note is issued by the Asset Standards Authority to clarify the intent of SPC 207

Track monitoring requirements for undertrack excavation and to provide further information

regarding the configuration conditions for buried services at turnouts and special trackwork.

SPC 207 identifies a surveillance procedure to adopt when disturbing the formation beneath an

existing track. The document has been specifically tailored for the design and installation of

underbores up to 450 mm diameter. However, the intent of the specification is to impose

monitoring of track position and surrounding infrastructure whenever there is potential to cause

displacement when undertaking any activity beneath, or adjacent to, the track. Such activities

cover various assets, including underbridge or platform renewals, embankment stabilisation,

trenching drainage pipes and major tunnelling works.

Where the scope includes track reconstruction, if a geotechnical assessment identifies there is

potential risk to displace the adjacent track(s), or differential settlement to occur with the

reconstruction, a monitoring regime shall be implemented. The monitoring shall continue after

works are complete for a period specified by the geotechnical assessment.

The design and installation of services by any method beneath turnouts and other special

trackwork, or within 10 m of their locality, is generally prohibited. See Section 8.2.5 of SPC 207

for further information. This includes drainage carrier pipes in trenches. Where this configuration

cannot be avoided, sufficient information shall be provided as a request for a concession to the

Lead Track Engineer, ASA.

For queries regarding this document [email protected]

www.asa.transport.nsw.gov.au

mailto:[email protected]

mailto:[email protected]

http://www.asa.transport.nsw.gov.au/

Technical Note - TN 004: 2015

© State of NSW through Transport for NSW of 2

Replace Section 3 of SPC 207 with the following:

Section 3 General description requirements

This specification contains requirements which are additional to the requirements for

management of service installations and works, as described in ESC 540 Service Installations

within the Rail Corridor.

If a geotechnical assessment ascertains that a risk to displacement of the track is possible, a

monitoring regime shall be implemented.

Monitoring is appropriate where incremental movement may occur within limits. Additional risk

management is required where there is a risk of gross collapse or track displacement equal to, or

greater than 4 mm, either vertically or horizontally.

If underboring is planned and it meets the requirements of minor underboring detailed in

Section 8.2, the simplified monitoring guidelines detailed in Section 8.3 may be applied. For any

other work with the potential to displace the track, or surrounding infrastructure, Sections 5, 6,

and 7 of this specification shall be applied.

Variation to the monitoring regime stated in this specification requires approval by the Lead Track

Engineer, ASA.

Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Name Neil Johnson Dave Cooper John Paff Graham Bradshaw

Position Principal Track Engineer

A/Lead Track Engineer

A/Chief Engineer Rail Director Network Standards and Services

Engineering Specification Track

SPC 207

TRACK MONITORINGREQUIREMENTS FOR

UNDERTRACK EXCAVATIONVersion 1.5

Issued April 2013

Reconfirmed 03 July 2019

Owner: Chief Engineer, Track

Approved by:

Andrew Wilson Technical Specialist Wheel/Rail

Authorised by:

Malcolm Kerr Chief Engineer Track

Disclaimer

This document was prepared for use on the RailCorp Network only.

RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the copy of the document it is viewing is the current version of the document as in use by RailCorp.

RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes any liability which arises in any manner by the use of this document.

Copyright

The information in this document is protected by Copyright and no part of this document may be reproduced, altered, stored or transmitted by any person without the prior consent of RailCorp.

En

gin

eeri

ng

Sp

ecif

icat

ion

UNCONTROLLED WHEN PRINTED Page 1 of 19

RailCorp Engineering Specification — Track Track Monitoring Requirements for Undertrack Excavation SPC 207

Document control

Version Date Summary of change 1.0 November, 2008 First issue 1.1 December, 2009 Format change; Section 2.2 - Additional RailCorp reference

documents; Section 2.4 – Additional definitions dealing with minor underboring; Section 3 - Addition of reference to minor underboring guidelines; Section 5.8 Table 1 Changes to reflect change in position titles; Section 6.1.3 Changes to reflect change in position titles; Section 7 Table 4 - Changes to reflect change in position titles; Section 8 - New section covering the requirements for monitoring of minor underboring

1.2 August, 2011 Section 1 - Scope widened to include works by all parties. Section 2.4 - Competencies updated to current National Competencies

1.3 September, 2011 Section 3 - Changes to restrict requirements for Chief Engineer Track approval to critical works. All other works may be approved by Civil Maintenance Engineers. Section 5.8 - Minor change to the sample distribution list

1.4 June, 2012 Reformatted to new template 1.5 April, 2013 Changes detailed in Summary table below

Summary of changes from previous version

Summary of change Section

Control Changes Document Control

Additional and changed definitions; Updated National Competencies 2.4

Changes to requirements 3

Addition to exclusions 4

Removal of actual persons from sample distribution list 5.8

Clarification of application of guidelines for minor underboring 8.1

New section – Minimum monitoring for underboring 9

Change of title; additional explanation in Applicability Appendix A

© RailCorp Page 2 of 19 Issued April 2013 UNCONTROLLED WHEN PRINTED Version 1.5

RailCorp Engineering Specification — TrackTrack Monitoring Requirements for Undertrack Excavation SPC 207

Contents

1 Scope and Application ...........................................................................................................4

2 References...............................................................................................................................4

2.1 Australian and International Standards.....................................................................................4

2.2 RailCorp Documents .................................................................................................................4

2.3 Other References......................................................................................................................4

2.4 Definitions .................................................................................................................................4

3 General Description and Requirements ...............................................................................5

4 Exclusions from this Specification .......................................................................................6

5 Monitoring................................................................................................................................6

5.1 Scope ........................................................................................................................................6

5.2 Location of Monitoring Points....................................................................................................6

5.3 Measurements ..........................................................................................................................6

5.4 Measurement Equipment and Accuracy...................................................................................8

5.5 Monitoring Frequency ...............................................................................................................8

5.6 RailCorp Measurements, Track Works & Maintenance............................................................8

5.7 Data Presentation .....................................................................................................................9

5.8 Distribution of Monitoring Data..................................................................................................9

6 Notification and Intervention Levels .....................................................................................9

6.1 Rail Monitoring Intervention Levels. ..........................................................................................9

6.2 Embankment and '6 foot' Monitoring Intervention Levels .......................................................12

7 Emergency Procedure..........................................................................................................12

8 Guidelines for Minor Underboring ......................................................................................12

8.1 General....................................................................................................................................12

8.2 Requirements for Minor Underboring......................................................................................12

8.3 Site Work and Monitoring........................................................................................................14

8.4 Management of Guidelines .....................................................................................................15

9 Minimum Monitoring for Underboring ................................................................................16

9.1 General....................................................................................................................................16

9.2 Track Monitoring .....................................................................................................................16

Appendix A Small Area Monitoring Requirements .................................................................17

Applicability.............................................................................................................................................17

Requirements .........................................................................................................................................17

Sample Measurements...........................................................................................................................18

Sample Monitoring Calculations.............................................................................................................18

Appendix B Large Area Monitoring Requirements .................................................................19

Applicability.............................................................................................................................................19

Requirements .........................................................................................................................................19

© RailCorp Page 3 of 19Issued April 2013 UNCONTROLLED WHEN PRINTED Version 1.5


1 Scope and Application This Specification sets out technical requirements for monitoring of railway infrastructure during undertrack excavation or any other construction work which has the potential to disturb the track. It includes survey requirements, monitoring of infrastructure movements, limits to be observed and reporting and data requirements.

Clauses in this standard specification may be altered or deleted by a site specific “Particular Specification”.

It is applicable for all works undertaken that may impact on the condition or stability of RailCorp’s rail infrastructure. Works undertaken by RailCorp track and structures maintenance teams may be excluded from the requirements of this specification.

2 References

2.1 Australian and International Standards Nil

2.2 RailCorp Documents ESC 210 – Track Geometry and Stability

ESC 540 – Service Installations within the Rail Corridor

TMC 001 – Civil Technical Competencies and Engineering Authority

TMC 203 – Track Inspection

TMC 211 – Track Geometry and Stability

SPC 211 – Survey Specification

2.3 Other References Nil

2.4 Definitions Underbore Bored underground service installation which passes beneath the

track

Minor underbore Underbore of a size and depth such as to have negligible impact on rail tracks and other rail infrastructure (specified in Section 8.2.1)

Sheathing: Boring can be either sheathed where a conduit is installed as part of the boring process or unsheathed where the hole is bored first and the conduit inserted into the bored hole.

Stiff Soils: For underboring it is important to establish whether the hole will be self-supporting during the boring process. Stiff soils such as stiff clay, shale, rock will be self-supporting. For these materials the hole can be bored without sheathing


3 General Description and Requirements


Contractor’s Person engaged by the contractor to measure and assess track Competent track geometry at the site. The person must be competent to Examine person and Certify track, possess current RailCorp competencies

“TLIB3100A - Visually inspect track infrastructure”, “TLIB3099A Examine track infrastructure” (see TMC 203) and “TLIB3094B Check and repair track geometry” (see TMC 211) and be acceptable to RailCorp

Contractor Person nominated by the contractor in the Site Specific Safety representative Plan as the contact for site activities affecting RailCorp

infrastructure

If, as a result of a design and works planning review as required by RailCorp Engineering Standard ESC 540 – "Service Installations within the Rail Corridor" and based on geotechnical report/s, RailCorp determines that ground movement is possible or expected as a result of the work, RailCorp may determine that track monitoring and risk management is required.

This specification contains requirements which are additional to the requirements for management of service installations and works, as described in Railcorp Standard ESC 540 and other relevant standards.

Track monitoring shall be undertaken in accordance with this specification, if a risk of track movement is identified. Variation to this specification may only be approved by the Chief Engineer Track.

Monitoring is appropriate where incremental movement may occur within limits Additional risk management is required where there is a risk of gross collapse.

If underboring is planned and it meets the requirements of 'minor' underboring detailed in Section 8.2, the simplified monitoring guidelines detailed in Section 8.3 may be applied. For any other work with potential to disturb the track, a detailed geotechnical investigation shall be undertaken to determine predicted track movement.

Except as noted below, projects meeting the requirements for minor underboring may be approved by Civil Maintenance Engineers and will not need to be submitted for integrity review by the Chief Engineer Track, Principal Geotechnical Engineer or their delegates. Their advice can, however, be sought if required.

The following installations shall be monitored and managed in accordance with Sections 5, 6 and 7, and may only be undertaken with the approval of the Chief Engineer Track or the relevant Civil Maintenance Engineer:

• Work at any location under, or within 10m of, turnouts or special trackwork (as catchpoints, expansion switches, diamonds, slips etc.)

• All underboring, excavation, piling, or jacking, or any work that has the potential to significantly affect track geometry (>4mm vertical or horizontal movement) on an operating track. This includes settlement during or following the work or where work is suspended following the passage of each train.

• Any underbore which is un-encased during the passage of trains, and does not meet the requirements of ‘minor’ underboring detailed in Section 8.2.

All other underbores shall be monitored and managed in accordance with Section 9.



4 Exclusions from this Specification This specification does not include RailCorp’s requirements for timing of works or protection of rail traffic by Worksite Protection.

This specification does not include requirements for monitoring of infrastructure other than track.

5 Monitoring

5.1 Scope During installation or excavation there is a risk of track movement due either to uplift as a structure is pushed into place, or settlement as the ground below or adjacent to the track is removed to progress installation or excavation

Throughout all installation or excavation a monitoring system shall be established, operated and subsequently removed. The system shall monitor track and embankment movements where movement could occur. The minimum requirements for monitoring of track are detailed in Appendix A. The requirements for longer installations are shown in Appendix B.

The constructor shall monitor the rail level and settlement of the embankment throughout the installation or excavation process to ensure the track remains safe for passage of trains. Embankments shall also be monitored locally during installation and subsequent excavation of soil.

5.2 Location of Monitoring Points The contractor shall provide a plan which identifies the locations of monitoring points on the track and embankments at the site.

Track

Survey targets shall be fixed (epoxy glued) to the rail web at these locations such that they are visible from the survey points. Small angle brackets shall be used (epoxy glued) to orientate the targets appropriately. Alternative methods shall be approved by the Chief Engineer Track. Survey points shall be set up in each quadrant, remote from the works and fixed by concreting prefabricated baseplates into the ground at suitable locations. This will reduce the risk of accidental movement of instrumentation and facilitate accurate and consistent relocation of instruments when necessary.

Embankment

In addition to rail monitoring, a number of points on the embankment shall be monitored. This will identify and quantify any settlement or movement of the ground due to excavation or jacking operations. Pegs shall be driven into the ballast and left protruding approximately 300mm above ground level and targets shall be fixed to these pegs.

5.3 Measurements

5.3.1 Preliminary Measurements (dilapidation survey)

Prior to commencement of installation or excavation works, a full set of track and embankment readings shall be taken and recorded as the baseline set. A minimum of two full sets of track and embankment readings should be taken on separate days. This



will enable greater confidence in the repeatability of the survey measurements. If the two sets do not provide enough agreement to satisfy RailCorp that the observations will be able to detect predicted movements in the required timeframe, then an alternative observation strategy shall be developed.

The track survey results shall be reviewed by the Contractor’s competent track person to establish permissible movements of track to reach defined action levels at each monitoring point.

NOTE: Unless otherwise agreed the Alarm levels include any pre-existing variations in geometry.

HOLD POINT

Track survey results and proposed action levels shall be approved by the RailCorp Civil Maintenance Engineer (or delegated maintenance representative) prior to commencement of installation.

5.3.2 Measurement During Works

Track

After commencement of installation, a continuous cycle of rail monitoring shall be carried out with the variances from the baseline readings compared to previously defined action levels.

Frequency of measurement shall be determined based on the extent of possible movement and the time over which it could occur. The nature of the work and traffic arrangements should also be considered.

The survey monitoring results shall be conveyed to site staff at appropriate intervals considering the remaining margin before actionable limits are reached.

During installation of underline crossings by jacking, two rail targets immediately above and in front of the end being jacked shall be continuously monitored. If any sudden movement is detected, action shall be taken in accordance with Section 6.1 - Rail Monitoring Intervention Levels. In addition the competent track person shall visually inspect the track and carry out measurements deemed applicable based on the visual assessment but measurement shall at least include superelevation at 2m intervals in the affected area. Measurements are to be assessed against track standards.

Embankment

The monitoring points on the embankment shall be monitored during installation or excavation works. This will identify and quantify any settlement or movement of the ground due to excavation or jacking operations.

The contractor shall collate and plot a graphical representation to illustrate changes in the following with time;

Leading edge location of forepoles (if applicable)

Leading edge location of the underpass (or underbore) structure

Excavation profile within the underpass (if applicable)

Movement of monitoring points



Continuous visual inspection of the embankment and internal excavation profile shall be carried out by the contractor to prevent any over excavation within the structure during installation and monitor any ground movements.

RailCorp may require the contractor to have a Geotechnical engineer available throughout the undertrack installation period to assist in interpretation of monitoring results.

5.4 Measurement Equipment and Accuracy The rail monitoring surveys shall be carried out by a RailCorp approved surveying service.

A Rail Survey Procedure shall be prepared that meets the requirements of RailCorp Specification SPC 211 Section 6 “Survey for track and other infrastructure” covering,

• Instrumentation • Instrument Calibration • Instrument Setup • Survey Targets • Observations • Levels • Reporting and comparison to Engineering Standard ESC 210: Track Geometry and

Stability and Engineering Manual TMC 203: Track Inspection.

Measurement of track geometry shall be undertaken using the methods of measurement and equipment detailed in TMC 203: Track Inspection.

This procedure shall be approved by RailCorp prior to commencement of the installation.

5.5 Monitoring Frequency Survey and track measurements shall be taken at frequencies agreed in the monitoring plan but not less frequently than daily:

• During Piling – monitoring pegs shall be driven into the cess adjacent to pile locations.

• During undertrack installation – monitoring shall be as described in Section 5.3.2 above.

In addition, after major undertrack installation, rail, cess and six foot targets shall be monitored daily for 2 days, weekly for one month then fortnightly for 3 months.

5.6 RailCorp Measurements, Track Works & Maintenance Track works and maintenance such as tamping and grinding has the potential to affect the position of tracks. Additional survey shall be required to determine the effect that this work has on track locations. Survey prior to and immediately following track maintenance would be appropriate.

RailCorp shall confirm when track work is to be carried out, with at least 48hrs notice to allow mobilisation of a monitoring team prior to maintenance works. The relevant maintenance or construction group shall perform its own survey monitoring and report back to the RailCorp Project Manager.



5.7 Data Presentation Data may be presented in numerical and graphical formats detailing lateral and vertical movements.

All result spreadsheets shall be accompanied with a covering report providing details for any site-monitoring visit including date of survey, time of survey, name of surveyor, temperature at commencement of survey, general weather conditions during the course of the survey and any remarks or comments relative to the survey. At least one daily report is required where track is being continuously monitored.

5.8 Distribution of Monitoring Data Data is to be processed and results provided to the RailCorp appointed person and to the Contractor’s Project Manager for distribution on a daily basis.

A Data Report Distribution List shall be established for each project. It shall take the form shown in Table 1.

Organisation Position Name Email address

Contractor Project Manager

RailCorp Maintenance Engineer

RailCorp Track Engineering Bob Smith [email protected]

RailCorp Chief Engineer Civil TBA If required for civil structures

RailCorp Project Manager

RailCorp Project Manager

RailCorp Geotech Services Allan Jones [email protected]

Table 1 – Sample Distribution List

6 Notification and Intervention Levels

6.1 Rail Monitoring Intervention Levels. Note: 1. the levels are not proportional limits (i.e. 25% is not 25% of normal limits)

Table 2 below identifies the default parameters and associated measurements being monitored during the construction period of the works. The values have been determined from RailCorp Standard ESC 210– Track Geometry Stability. Any higher values to be used must be identified in the monitoring plan approved by the Chief Engineer Track.


Monitoring Parameters

Normal limits

Track Speed (Normal /XPT) km/hr

20/20 40/40 60/60 80/90 100/115 115/160

100% (ie the next mm down from) (Note 1)

Top (4m) 27 24 21 18 14 14 Line (8m) 36 27 19 14 11 11 Short Twist (2m) 18 16 15 13 11 11 Long Twist (14m) 52 46 40 35 30 30 75% (Note 1)

Top (4m) 23 21 18 16 12 12 Line (8m) 31 23 16 12 10 10 Short Twist (2m) 16 14 13 11 10 10 Long Twist (14m) 45 40 35 30 26 26 50% (minimum 6mm) (Note 1)

Top (4m) 17 15 13 11 9 9 Line (8m) 22 17 12 9 7 7 Short Twist (2m) 11 10 9 8 7 7 Long Twist (14m) 32 28 24 21 18 18 25% (minimum 5mm) (Note 1)

Top (4m) 14 12 11 9 7 7 Line (8m) 18 14 10 7 6 6 Short Twist (2m) 9 8 8 7 6 6 Long Twist (14m) 26 23 20 18 15 15


Note: 1. the levels are not proportional limits (i.e. 25% is not 25% of normal limits)

Table 2 - Normal limits for track monitoring

Alarm Level 1 2 3

> 25% but ≤ 50% of Normal limit

> 50% but ≤ 75% of Normal limit

sudden movement > 50% of Normal limit

Table 3 - Default Alarm levels

The Chief Engineer Track may approve amended limits to account for local design and condition features.

6.1.1 Alarm Level 1

Any detected movement > 25% but ≤ 50% of Normal Limits or where significant movements have been detected above those predicted.

Measurements

Verify movement by reviewing and repeating the survey. The competent track person shall carry out an immediate survey of track line and top to confirm movement and assess track geometry.

Notification

Notify all parties following detection of movement.

Continuation of works

If settlement has exceeded the predicted settlement the Geotechnical Engineer is to reassess and, if appropriate, approve continuation of the work. On approval by the



Geotechnical Engineer, works shall not stop at this point but shall proceed with caution and increased vigilance in the areas of detected movement.

6.1.2 Alarm Level 2

Any detected movement > 50% but ≤ 75% of Normal Limits where movement has been steady. (See below for sudden movements).

Measurements

Verify movement by reviewing and repeating the survey. The competent track person shall carry out an immediate survey of track line and top to confirm movement and assess track geometry.

Notification



The Geotechnical Engineer shall reassess and, if appropriate, recommend continuation of the work. If the Geotechnical Engineer does not recommend continuation of the works, he shall determine remedial measures to be implemented prior to re-commencement of the works, to prevent further settlement. Work must not proceed unless approval has been given by the Civil Maintenance Engineer for work that will exceed Alarm Level 3.

6.1.3 Alarm Level 3

If movement preceding this level have been gradual, alarm levels 1 and 2 control measures shall have been introduced to prevent this level of movement occurring. Consequently, the control measures identified for level 3 are identified on the basis of a sudden movement only.

If a sudden movement of > 50% but ≤100% of Normal Limit is detected:

Notification



All works will cease immediately. Works shall not recommence until methodology and monitoring procedures are reviewed and remedial measures/revisions, are approved by the Civil Maintenance Engineer.

If a sudden movement of >100% of Normal Limit is detected:

Notification

Apply emergency procedures immediately. Notify all parties.


All works will cease immediately. The competent track person shall assess the track geometry and take appropriate action. This may include speed restrictions and consultation with RailCorp’s Civil Maintenance/Senior Civil Engineer. Works shall not recommence until methodology and monitoring procedures are reviewed, remedial measures/revisions are approved by RailCorp (Principal Geotechnical Engineer and Chief Engineer Track) and track geometry corrective works have been undertaken.



6.2 Embankment and '6 foot' Monitoring Intervention Levels The targets placed along the bottom of the embankments or at other locations shall be monitored at the same frequency as the track (or at greater frequency if required). Alarm levels must be determined as part of the geotechnical assessment and must be included in the monitoring plan.

7 Emergency Procedure In the event of an emergency, the competent track person shall immediately stop trains and notify Train Operations in accordance with RailCorp Standards and Procedures.

The Contractor representative on site shall notify the people on the Emergency Contact List.

An emergency contact list shall be established for each project. It shall take the form of the example shown in Table 4.

The following contacts should be advised of the emergency in the order shown,

Order Organisation Contact Name Position Contact Number 1 RailCorp Train

Operations Fred Smith Superintendent 0411 234 056

2 Emergency Services 000 3 RailCorp Isaac Jones Project Manager 0421 657 430 4 RailCorp Bill Mendes Project Officer 0414 365 987 5 RailCorp Simon Ford Senior Civil

Engineer 0411 556 998

6 RailCorp Harry Short Maintenance Engineer

0412 478 883

7 Contractor 1 John Jacobs Project Manager 0411 336 779 8 Contractor 2 Lee Sound Project Manager 0412 337 455

Table 4 - Sample Emergency Contact List

The Contractor representative on site shall undertake all tasks to ensure site and train operation safety during the interim while RailCorp initiate their Emergency Response Procedure.

8 Guidelines for Minor Underboring

8.1 General The following simplified guidelines address track and geotechnical requirements for minor underboring, and allow for a reduced level of geotechnical investigation. Monitoring of track movements and other requirements are reduced as detailed below.

The guidelines only address the requirements for the underboring activity. The type of crossing (such as for water and gas pipelines) may require additional assessment including of future safety and stability and shall be managed in accordance with the requirements of ESC 540 - Service Installations within the Rail Corridor.

8.2 Requirements for Minor Underboring To be classified as minor underboring work and be eligible to utilise the simplified guidelines, the following conditions must be met:


8.2.1 Pipe Diameter and Depth Limits

There following limits on the pipe diameter and the depth below rail level apply: (See Figure 1)

• the top of the pipe MUST be at least 2m below rail level • the maximum pipe diameter is 450mm • at 2m below rail level the maximum pipe diameter is 100mm. • at 4.5m below rail level the maximum pipe diameter is 450mm. • between 2m and 4.5m below rail level, the maximum pipe diameter may be

increased proportionally between 100mm and 450mm. • Underbores must be a minimum of two metres below the natural ground level

either side of an embankment (See Figure 2).

Rail Level

Depth to be at least 2m below rail

Pipe depth and size 4.5m permitted within this envelope

Pipe no more than 450mm diameter

Largest pipe at 2m depth is 100mm diameter

2m

Figure 1 – Permitted Depth

roundevel Ground

level

G L

Underbore to be a minimum of 2m below ground level


Figure 2 - Permitted Depth at Embankments

8.2.2 Geotechnical Assessment

All underboring must be assessed by a geotechnical engineer. The assessment must establish:



• if the soil material can be established as stiff and will be self supporting or otherwise,

• whether any additional testing and/or excavation is required, including determination of soil characteristics

• any site features or characteristics that would bear on the prospective ground/ track settlement.

8.2.3 Sheathing and Stiff Soils

Where stiff soils are encountered for the full length of the underbore, sheathing is not required. Where soils are not stiff, or where conditions are not known, underbores must be sheathed.

8.2.4 Structures

All structures, masts, buildings, power poles etc. must be at least 2m clear horizontally from the zone of influence (45°upwards from the pi pe).

Note that there additional clearance requirements both vertical and horizontal depending on the particular services involved.

8.2.5 Proximity to Turnouts or Special Trackwork

No underboring can be carried out at any location under, or within 10m of turnouts or special trackwork (catchpoints, expansion switches, diamonds, slips etc.).

8.3 Site Work and Monitoring It is important that there is sufficient control and supervision of the site work to ensure there is no impact on the railway. Minimum requirements are detailed below.

8.3.1 Boring Requirements

The boring contractor must be a substantial organisation with demonstrated experience in underboring under railways or equivalent sensitive structures.

Systems and controls must be in place that ensure the boring hole follows the design path for the length of the bore. Above ground tracking equipment should be applied where the location cannot be accurately determined from the driving control.

8.3.2 Geotechnical Supervision

Work must be supervised by a geotechnical engineer to confirm the boring is proceeding as expected and the material being excavated is as expected. The geotechnical supervisor must also verify the completion of the work to plan including consideration of any movements detected. The geotechnical engineer must identify any potential problems or possible future unexpected settlement.

The findings must be reported to the nominated contact from the track maintenance organisation.

8.3.3 Site Security

Site planning must ensure that the site remains safe at all times including:

• if the site has to be vacated due to suspension of the work (occurring over multiple days), or



• in the event of extreme weather conditions, such as heavy rain, affecting the site.

The boring operation must be managed so that it is not vulnerable to rain or extreme weather events, including when staff are absent.

8.3.4 Safety Supervision

A worksite protection officer must be present (minimum PO1). The protection officer can respond to any irregularity by suspending train operation.

For lines where there are train running sensitivities it is recommended that a track assessor (minimum qualification RailCorp “Maintain Track Geometry”) is also present. The track assessor can respond to any irregularity by assessing the track condition and applying appropriate restrictions.

The worksite protection officer and the track assessor can be the same person.

8.3.5 Track Monitoring

1. The minimum monitoring required is the measurement of vertical movement of the rail during the underboring operation. This can be achieved by applying a precisely located paint mark on the web of each rail directly above the underbore. As an alternative the top of the rail can be monitored with a survey staff but this will require appropriate track protection. Monitoring must be carried out with an accuracy of ± 2mm by staff competent to use the relevant equipment.

2. The operation may only be continued if the track movement due to boring is negligible (i.e. ≤ 4mm). If > 4mm track movement occurs work must cease and track maintenance staff notified.

3. Monitoring pegs must also be placed in the ground clear of ballast on the approach to the track (and including the sides and top of any embankment) to verify that there is no unexpected ground movement.

4. Monitoring shall be carried out at least hourly whilst underboring is at or near the track and at the end of the day before leaving the site. The minimum level of follow up monitoring shall be readings after one day of rail traffic.

5. Track maintenance staff must be notified where minor underboring has been carried out and they will monitor the track during normal patrol inspections.

8.3.6 Train Operations

For minor underboring carried out within these guidelines the work can be carried out under traffic. If trains are frequent (i.e. more than 2 per hour) monitoring should be increased to half hourly.

8.4 Management of Guidelines The requirements of the guidelines for minor underboring shall be managed by the relevant District Maintenance Office, relevant coordinating group (such as External Party Works) and utilising the configuration management process.

Determination that a proposed underbore may be categorised as a 'minor' underbore may only be made by a Civil Maintenance Engineer or Senior Civil Engineer who has been delegated Design Authority for the activity in accordance with RailCorp Engineering Manual TMC 001 – Civil Technical Competencies and Engineering Authority.



9 Minimum Monitoring for Underboring

9.1 General These requirements apply to any underboring which does not require monitoring in accordance with Sections 5, 6, 7 or 8 of this specification. They are intended to address the risk of unpredicted movement from underbores where a negligible movement prediction (i.e. ≤ 4mm) has been given.

9.2 Track Monitoring 1. The minimum monitoring required is the measurement of vertical movement of

the rail during the underboring operation. This can be achieved by applying a precisely located paint mark on the web of each rail directly above the underbore. As an alternative the top of the rail can be monitored with a survey staff but this will require appropriate track protection. Monitoring must be carried out with an accuracy of ± 2mm by staff competent to use the relevant equipment.

2. The operation may only be continued if the track movement due to boring is negligible as predicted (i.e. ≤ 4mm). If > 4mm track movement occurs work must cease and track maintenance staff notified.

3. Monitoring pegs must also be placed in the ground clear of ballast on the approach to the track (and including the sides and top of any embankment) to verify that there is no unexpected ground movement.

4. Monitoring shall be carried out at least daily whilst underboring is at or near the track and at the end of the day before leaving the site. The minimum level of follow up monitoring shall be readings after one day of rail traffic.

5. Track maintenance staff must be notified where any underboring has been carried out and they will monitor the track during normal patrol inspections.



Appendix A Small Area Monitoring Requirements

Applicability This measurement regime is used where a small area of disturbance is involved.

If the predicted movement for an underbore is less than that required to produce an Alarm Level 2 condition (as defined in Section 6.1.2 and taking into account existing track conditions), then track monitoring may be limited to levels on each rail above the underbore centreline.

If movement occurs which exceeds the predicted amount, and in all other cases with a small area of disturbance, monitoring shall be implemented which It measures potential vertical movement 4m either side of the "0" point and horizontal movement 2m either side, as shown below:

Requirements

Initial Measurements (+ve away from Sydney where 0 is CL of bore) Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

V (down) i m m m m m i

V (up) i m m m m m i

Superelevation i i i i c c c c c i i i i

H (down) i i m m m i i

H (up) i i m m m i i

Gauge c c c c c

Design Versine (mm) d d d

Where m = measure

c = calculate

i = initial measurement only

d = design versine for mid-ordinate of 8m chord in mm. radius(m)

8000 d =

H is a reference horizontal position perpendicular to the track

V is a reference vertical level

Monitoring Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

Tw (14) Sydney c c c

Tw (14) Country c c c

Top 4m dn c c c c c

Top 4m up c c c c c

Tw (2m) Country c c c c c c

Line 8m dn c c c

Line 8m up c c c

Gauge* c c c c c

* gauge only if required


Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

Tw (14) Sydney -30 -25 -25

Tw (14) Country -15 -20 -25

Top 4m dn -1 2.5 -2.5 2.5 0

Top 4m up 0 -2.5 2.5 -2.5 2.5

Tw (2m) Country 3 5 0 5 0 0

Line 8m dn -2.5 0 0

Line 8m up -7.5 -2 1

Gauge* 1436 1440 1440 1435 1440

Dsgn Line Versine 8m 5 5 5

Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

V (down) 0 5 15 8 0

V (up) 0 15 10 0 0

Superelevation 0 10 -5 -8 0

H (down) 0 0 -2

H (up) 1 0 -3

Gauge 0 1 0 -1 0

where +ve indicates, movement vertically downwards, horizontally to the down side and gauge widening


Sample Measurements Sample Initial Measurements Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

V (down) 200 190 185 180 167 160 150

V (up) 208 195 185 180 162 155 145

Superelevation 30 25 20 8 5 0 0 -5 -5 -5 -15 -20 -30

H (down) 3000 3010 3020 3025 3035 3040 3050

H (up) 4435 4446 4460 4465 4470 4480 4482

Gauge 1436 1440 1440 1435 1440

Monitoring

Sample Monitoring Measure Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

V (down) 200 190 190 195 175 160 150

V (up) 208 195 200 190 162 155 145

Superelevation 30 25 20 8 5 10 -5 -13 -5 -5 -15 -20 -30

H (down) 3000 3010 3025 3030 3038 3040 3050

H (up) 4435 4446 4466 4470 4472 4480 4482

Gauge 1436 1441 1440 1434 1440

Sample Monitoring Calculations Parameter Movements

Defect Criteria Calculations Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

Tw (14) Sydney -20 -30 -33

Tw (14) Country -25 -15 -17

Top 4m dn 4 -10 3.5 8 -4

Top 4m up 2.5 -5 1.5 -3 4

Tw (2) Country 3 -5 15 8 -8 0

Line 8m dn -6 -5 -0.5

Line 8m up -12.5 -7 2

Gauge* 1436 1441 1440 1434 1440 Based on using 8m chord for alignment 4m chord for top (using AK Car [1.8m offset on 10m chord] values for 4m chord)



Appendix B Large Area Monitoring Requirements

Applicability This measurement regime is used where larger areas of possible disturbance are involved.

It measures potential vertical movement 4m either side of the disturbed area (A1 to An) point and horizontal movement 2m either side of the disturbed area (A1 to An).

RequirementsInitial Measurements (+ve away from Sydney where A1 to An is extent of disturbance)

Monitoring Point -16 -14 -12 -10 -8 -6 -4 -2 A1 A2 A3 A4 A5 A6 …. An 2 4 6 8 10 12 14 16

V (down) i m m m m m m m m m m m m i

V (up) i m m m m m m m m m m m m i

Superelevation i i i i c c c c c c c c c c c c i i i i

H (down) i i m m m m m m m m m m i i

H (up) i i m m m m m m m m m m i i

Gauge c c c c c c c c c c c c

Design Versine (mm) d d d d d d d d d d

Where m = measure

c = calculate

i = initial measurement only

d = design versine for mid-ordinate of 8m chord in mm. d = 8000 radius(m)

H is a reference horizontal position perpendicular to the track

V is a reference vertical level
